A development server toolkit for the Uno platform, made up of a command-line tool, a background host process, and an MCP proxy for connecting AI agents.

Use it to build, test, and maintain the Uno DevServer code, its CLI commands, its IDE channel, its MCP connection, and its add-in resolution.

It gives Uno DevServer work a defined place for managing server startup, stopping, ports, IDE connections, Hot Reload, and add-in discovery.

devserver — Skill by unoplatform

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods

npx agentmods add skills/unoplatform/uno/devserver

Any agent

npx skills add unoplatform/uno --skill devserver

Clone the repo

git clone --depth 1 https://github.com/unoplatform/uno

Made for: Claude Code, Codex.

Per session 79 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 2,209 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. Scan, not verified.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5	$0.00079	$0.02209
Opus 5	$0.00039	$0.01104
Sonnet 5	$0.00016	$0.00442
Haiku 4.5	$0.00008	$0.00221

Measured 2d ago against content hash f96b40e9b707, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

devserver scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.claude/skills/devserver/SKILL.md · 96 lines

How it starts

The opening of the file, as written. The whole thing — 96 lines — stays where its author put it; the contents beside it link to each section on GitHub.

DevServer (CLI / Host / MCP)

Maintain and extend the Uno DevServer: the CLI tool, the Host process, MCP proxy integration, and add-in discovery. The DevServer projects are independent of the UI framework and do not require crosstargeting_override.props.

1. Architecture — a 2-process chain

CLI (Uno.UI.DevServer.Cli) – entry point, user-facing commands, MCP STDIO proxy, start-lifecycle management.
Host (Uno.UI.RemoteControl.Host) – ASP.NET Core server for Hot Reload, IDE channel, processors.

The CLI start command handles existing-server detection (AmbientRegistry), IDE channel rebinding, port allocation, and launches the Host in direct mode (no --command), so all arguments (including --ideChannel) reach the Host via IConfiguration regardless of Host binary version. Non-start commands (stop, list, cleanup) use the Host's controller mode (--command=<verb>). The CLI can also run in MCP mode (--mcp-app) as a Model Context Protocol proxy between AI agents and the running Host.

Packages

NuGet Package	Contents
`Uno.DevServer`	CLI tool (installed via `dotnet tool`)
`Uno.WinUI.DevServer`	Host binaries, processors, BuildTransitive targets

2. Source map

Directory	Purpose
`src/Uno.UI.DevServer.Cli/`	CLI tool: commands, helpers, MCP proxy
`src/Uno.UI.DevServer.Cli/Helpers/`	Discovery, caching, process helpers
`src/Uno.UI.DevServer.Cli/Mcp/`	MCP server, client proxy
`src/Uno.UI.RemoteControl.Host/`	Host process: server, extensibility, IDE channel
`src/Uno.UI.RemoteControl.Host/Extensibility/`	Add-in loading and discovery
`src/Uno.UI.RemoteControl.DevServer.Tests/`	Unit and integration tests
`build/test-scripts/`	PowerShell integration test harness
`build/nuget/Uno.WinUI.DevServer.nuspec`	NuGet package definition

Key files: CliManager.cs (command router), UnoToolsLocator.cs (SDK/package discovery from global.json, NuGet cache, AmbientRegistry), TargetsAddInResolver.cs (fast add-in discovery via .targets XML), ManifestAddInResolver.cs (manifest-first discovery from devserver-addin.json), DotNetVersionCache.cs, McpStdioServer.cs, ProxyLifecycleManager.cs, McpUpstreamClient.cs, ToolListManager.cs, DevServerMonitor.cs (+ MonitorDecisions.cs, pure decision logic for testability), HealthService.cs/HealthReport.cs, DiscoveryIssueMapper.cs, ConnectionState.cs, SolutionFileFinder.cs; Host: RemoteControlServer.cs (WebSocket server, processors), AddIns.cs (discovery + assembly loading).

Read the full file on GitHub · 96 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

2d ago First seen · 96 lines · 79 tokens per session scan A f96b40e9b707

Subscribe to this mod's changes

devserver is a skill published in the GitHub repository unoplatform/uno (10,024 stars, last pushed 2d ago), licensed Apache-2.0. It adds 79 tokens to every session and 2,209 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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